JP2012218142A - Joint structure, robot, and method of operating joint structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the influence of a frictional force applied to a member when the member is separated from a ground surface.SOLUTION: A joint structure 100 includes a heel portion (first member) 50 and a toe (second member) portion 20, both being separated from a ground surface in this order. The heel portion 50 has a rotating shaft AX engaged with the toe portion 20, the rotating shaft AX being so structured that it can move on the toe portion 20 along the ground surface in accordance with the rotation of the heel portion 50 relative to the toe portion 20. The rotating shaft AX is structured to be movable in an arrowed direction parallel with the X axis, thus the shaft AX moves on the toe portion 20 along the ground surface in synchronization with the rotation of the heel portion 50 relative to the toe portion 20. Adopting this configuration realizes an operation of separation from the ground surface in a mode where the influence of a frictional force is suppressed.

Description

  The present invention relates to a joint structure, a robot, and a method for operating the joint structure.

  Although robots are used in various fields, in recent years, partner robots for the purpose of nursing care / assistance / entertainment have attracted attention. Since human living environments / living spaces vary, partner robots may be required to have the same walking characteristics as humans.

  Patent Document 1 discloses that a toe portion is provided in a foot structure of a robot, thereby improving the movement capability of the robot. FIG. 2 of Patent Document 1 discloses that the position of the ankle increases by bending the toe and the leg length is substantially extended. It is also disclosed that the leg length is changed by the toe movement (see also paragraph 0051 of the same document).

  Patent Document 2 discloses a jumping robot that secures a stationary state at the time of non-jumping by a flat foot contacting a floor with a flat surface. As shown in FIG. 5 of Patent Document 2, the toe 12 and the foot 16 are engaged with each other via a shaft. Paragraph 0013 of Patent Document 2 discloses that the swing angle of the toe 12 with respect to the foot 16 is adjusted by an electric motor.

  Patent Document 3 discloses a structure of a foot by providing a movable foot piece to adjust the ratio A / B disclosed in FIG. 1 of Patent Document 3 (FIGS. 4 and 6 of the same document). , 8 as well: In each figure, it can be seen that the positions of the foot pieces 102A to 102D have changed).

JP 2005-153038 A Japanese Unexamined Patent Publication No. 2007-7798 JP-A-5-318337

  When a foot part configured by providing a toe part with respect to the foot part is floated from the ground contact surface, it is necessary to control the rotation of the foot part with respect to the toe part in the ground state. In this case, a frictional force in a direction opposite to the moving direction of the same part is applied to the foot part in the grounded state, and it is required to generate a torque sufficient to overcome the frictional force. . Thus, when the foot part provided with the toe part with respect to the foot part is floated from the ground contact surface, a relatively large frictional force may be applied to the foot part.

  As apparent from the above description, when the target member is separated from the ground contact surface, it is strongly desired to suppress the frictional force applied to the target member. In addition, the above description is made mainly for the background explanation on which the present invention was born. The joint structure according to the present invention can be applied to various uses other than the feet of the robot, and the present invention is not allowed to be limitedly interpreted based on the above description.

  The joint structure according to the present invention is a joint structure including first and second members that are separated in this order from the ground plane, and the first member includes a rotating shaft engaged with the second member. The rotation shaft is configured to be movable on the second member along the grounding surface in accordance with the rotation of the first member with respect to the second member.

  The rotary shaft provided on the first member is engaged with the second member, and the rotary shaft is movable on the second member. The rotation shaft moves on the second member in accordance with the rotation of the first member relative to the second member. As a result, when the first member is separated from the ground surface, the first member can roll on the ground surface, and the separation operation from the ground surface can be realized in a manner in which the influence of the frictional force is suppressed. It becomes.

  The first member includes a shaft holding portion that holds the rotation shaft, and the shaft holding portion is configured to be able to rotate on the ground surface in accordance with the rotation of the first member with respect to the second member. Have been, and good.

  The first member includes a shaft holding portion that holds the rotation shaft, and the shaft holding portion is configured to be able to rotate on the ground surface in accordance with the rotation of the first member with respect to the second member. The joint structure according to any one of the above, further including a rotation ratio adjustment mechanism that adjusts a rotation ratio between the rotation shaft and the shaft holding portion.

  The first member includes a pair of shaft holding portions that hold the rotating shaft, and the first and second members interfere with each other during the movement of the rotating shaft between the pair of shaft holding portions. It is preferable that a space for avoiding this is provided.

  The first and second members may be provided with a guide mechanism for guiding the movement of the rotating shaft.

  The first member may include a pinion provided on the rotating shaft, and the second member may include a rack meshed with the pinion.

  In a mode that allows rotation between the first member and the second member, a link mechanism that connects the first and second members is further provided, and the first member is included in the link mechanism. It is preferable that a drive mechanism for moving the link forward and backward as viewed from the first member is provided.

  The second member may include a tip portion that is grounded with respect to the ground surface, and a guide portion provided with a moving path of the rotation shaft.

  An elastic member may be provided on the bottom surface of the first member.

  The first member may be a heel corresponding to a human foot heel, and the second member may be a toe corresponding to a human toe.

  The robot according to the present invention includes any one of the joint structures described above.

  The operation method of the joint structure according to the present invention includes first and second members that are sequentially separated from the ground contact surface, and the rotation structure provided on the first member is engaged with the second member. In accordance with the rotation of the first member relative to the second member, the rotation shaft moves on the second member along the grounding surface, and the body is moved relative to the second member. In response to the rotation of the first member, the first member rolls on the ground contact surface.

  According to the present invention, it is possible to realize the separation operation from the ground plane in a manner in which the influence of the frictional force is suppressed.

1 is a schematic perspective view of a joint structure according to a first embodiment. 1 is a schematic perspective view of a joint structure according to a first embodiment. 1 is a schematic top view of a joint structure according to a first embodiment. 1 is a schematic top view of a joint structure according to a first embodiment. 1 is a schematic side view of a joint structure according to a first embodiment. FIG. 3 is a schematic side view / sectional schematic view of the joint structure according to the first embodiment. FIG. 6 is an explanatory diagram for explaining adjustment of a rotation ratio according to the first embodiment. 1 is a schematic top view of a joint structure according to a first embodiment. 1 is a schematic cross-sectional schematic view of a joint structure according to a first embodiment. 1 is a schematic perspective view of a joint structure according to a first embodiment. 1 is a schematic perspective view of a joint structure according to a first embodiment. FIG. 6 is a schematic side view of a joint structure according to a second embodiment. FIG. 6 is a schematic diagram of a robot according to a third embodiment. It is explanatory drawing for reference explanation. It is explanatory drawing for reference explanation. It is explanatory drawing for reference explanation. It is explanatory drawing for reference explanation. It is explanatory drawing for reference explanation.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. A joint structure 100 according to the present embodiment is a structure in which a heel part (first member) 50 and a toe part (second member) 20 are rotatably engaged via a rotation axis AX (FIGS. 1 to 3). (See FIG. 4). The rotation axis AX is configured to be movable in the direction of an arrow parallel to the X axis (see FIGS. 1 to 4), and the rotation axis AX is synchronized with the rotation of the flange portion 50 with respect to the toe portion 20. It moves on the portion 20 (see FIG. 5: the interval from the rear end position of the toe portion 20 to the rotation axis AX satisfies W11 <W21 <W31). By configuring the joint structure 100 in this manner, it is possible to realize the separation operation from the ground plane in a manner in which the influence of the frictional force is suppressed. In short, the torque required to lift the collar unit 50 from the ground plane can be reduced, and the power consumption required to move the robot can be reduced. When the joint structure 100 is attached to a moving body (for example, a robot), the moving ability can be improved.

  Hereinafter, a specific description will be given with reference to FIGS. In each drawing, XYZ coordinates are set as necessary. The X axis coincides with the traveling direction of the joint structure 100, the Y axis coincides with the width direction of the joint structure 100, and the Z axis coincides with the vertical direction. Terms indicating directions such as up, down, left and right are premised on the front view of the drawing. The terms front and rear should in principle be understood with reference to the direction of travel of the joint structure 100.

  1 and 2 are schematic perspective views of the joint structure. 3 and 4 are schematic top views of the joint structure. FIG. 5 is a schematic side view of the joint structure. FIG. 6 is a schematic side view / sectional schematic view of a joint structure. FIG. 7 is an explanatory diagram for explaining the adjustment of the rotation ratio. FIG. 8 is a schematic top view of the joint structure. FIG. 9 is a schematic cross-sectional schematic view of a joint structure. 10 and 11 are schematic perspective views of the joint structure.

  As shown in FIGS. 1 to 4, the joint structure 100 includes a toe portion 20 and a heel portion 50. The toe part 20 and the heel part 50 are connected by a link mechanism 30. As shown in FIG. 2, the link mechanism 30 includes a joint 31, a link 32, a joint 33, and a link 34.

  As shown in FIG. 1, the toe portion 20 includes a tip portion 21 shaped like a nail and a guide portion 22 that provides a moving path of the rotation axis AX. The tip portion 21 includes a flat plate 21a, a flat plate 21b, and three arch portions 21c. The flat plate 21a is a flat plate-like member located in the xy plane. The flat plate 21b is a flat plate-like member located in the zy plane, and is provided upright perpendicular to the flat plate 21a. The arch portion 21c is an arch-shaped portion that connects the tip portion of the flat plate 21a and the upper end portion of the flat plate 21b.

  As shown in FIG. 2, the guide portion 22 has a frame-shaped portion 22b and a frame-shaped portion 22c erected with respect to the flat plate portion 22a, and the frame-shaped portion 22b and the frame-shaped portion 22c are connected by a beam portion 22d. It has a structure. The flat plate portion 22a is a flat plate-like member located in the xy plane. The frame-shaped part 22b is a frame-shaped part located in the XZ plane. The frame-like portion 22b includes a columnar portion extending in the x-axis direction and a columnar portion extending in the z-axis direction. The configuration of the frame-shaped portion 22c is substantially the same as that of the frame-shaped portion 22b. The tip side portions of the flat plate portion 22a, the frame-shaped portion 22b, and the frame-shaped portion 22c are connected to the back surface of the flat plate 21b (see FIG. 11).

  As will be understood from the description below, the guide portion 22 is provided with a guide rail, a rack, and a guide rail along the rotation axis AX, and thereby, a slider, a pinion, The displacement of the slider in the x-axis direction is preferably guided.

  As shown in FIG. 2, the flange 50 includes a base plate 53, a transmission (rotation ratio adjusting mechanism) 41, a slider 42 (see FIG. 6B), a pinion 43, a slider 44, and a top plate 80. Driving parts such as an electric motor 61, a pulley 62, a pulley 63, a belt 64, and a nut part 65 are mounted on the flange 50. The link 34 and the nut portion 65 constitute a so-called “ball screw”. The feed amount of the link 34 (in other words, the position of the nut portion 65 on the link 34) is adjusted by the rotation of the nut portion 65, so that the inclination of the flange portion 50 with respect to the toe portion 20 in the grounded state can be adjusted. Become.

  In addition, you may grasp | ascertain the collar part 50 including the drive components (The electric motor 61, the pulley 62, the pulley 63, the belt 64, and the nut part 65) mounted in the base board 53. FIG. The link mechanism 30 including the nut portion 65 may be grasped. A drive mechanism / drive means is realized by the drive source (electric motor 61) and the transmission mechanism (pulley 62, pulley 63, belt 64, nut portion 65). The feed amount of the link 34 included in the link mechanism 30 is adjusted by the drive mechanism. In addition, the recognition aspect of the superordinate concept including each member is various, and should not be limited to the superordinate concept described in the present embodiment.

  Again, the flange 50 is mounted with a “ball screw” composed of a link 34 that functions as a screw shaft and a nut portion 65 that functions as a nut. The feed of the link 34 is controlled by the rotation control of the nut portion 65 by the electric motor 61, and the inclination adjustment of the flange portion 50 with respect to the toe portion 20 is executed.

  As shown in FIG. 2, the base plate 53 of the flange portion 50 is a flat plate-like member located in the xy plane. The base plate 53 includes a pair of shaft holding portions 55 and 56 extending from the flat plate portion toward the toe portion 20 side. The shaft holding portion 55 includes an extending portion 55a extending linearly along the x-axis and a circular portion 55b having a circular shape in side view provided at the tip of the extending portion 55a. Similarly, the shaft holding portion 56 has an extending portion 56a extending linearly along the x-axis and a circular portion 56b provided at the tip of the extending portion 56a. The center points of the circular portions 55b and 56b are arranged on the rotation axis AX.

  On the flat plate portion of the base plate 53, a wall portion 57a, a column portion 57b, a wall portion 57c, a column portion 57d, a column portion 57e, and a wall portion 57f are erected. A pulley 63 and a nut portion 65 are disposed between the wall portion 57a and the wall portion 57c. The nut portion 65 is not fixed to the wall portion 57c and is in a rotatable state. The top plate 80 is strongly fixed on the flange 50 by the wall 57a, the column 57b, the wall 57c, the column 57d, the column 57e, and the wall 57f. In addition, the fixing method of the top plate 80 with respect to the collar part 50 is arbitrary.

  An electric motor 61 fixed on the flat plate portion of the flange portion 50 is disposed on the rear surface of the wall portion 57f. A pulley 62 is provided on the front surface of the wall portion 57f. The rotating shaft of the electric motor 61 and the rotating shaft of the pulley 62 are connected. By driving the electric motor 61, the pulley 62 is rotated in the yz plane. The pulley 62 and the pulley 63 are disposed on the same yz plane, and both are wound around a common belt 64. The rotating shaft of the pulley 62 and the rotating shaft of the pulley 63 are parallel to each other. The belt 64 is, for example, a toothed belt. The pulleys 62 and 63 are formed with continuous teeth in the circumferential direction, and these teeth are meshed with the teeth of the belt 64. The pulley 63 functions as a driven pulley in comparison with the pulley 62. The pulley 63 is fixed in position with respect to the nut portion 65, and the rotational force received by the pulley 63 is transmitted to the nut portion 65. As the nut portion 65 rotates, the advance / retreat (front-rear position) of the link 34 is adjusted.

  As shown in FIGS. 2 and 4, a link mechanism 30 is provided between the heel part 50 and the toe part 20. As described above, the link mechanism 30 includes the joint 31, the link 32, the joint 33, and the link 34. The joint 31 is a connecting portion between the tip 21 and the link 32. The joint 33 is a connecting portion between the link 32 and the link 34. The links 32 and 34 are shaft-like members extending linearly. The tip 21 and the link 32 are connected via the joint 31 so as to be swingable in the xz plane. Via the joint 33, the link 32 and the link 34 are connected so as to be swingable in the xz plane. The degree of freedom of each joint is arbitrary, and two or more degrees of freedom may be given.

  As shown in FIG. 4, the link 32 is provided in association with the guide portion 22. The link 34 is provided in association with the collar unit 50. When the toe portion 20 and the heel portion 50 are in contact with the ground, the link 32 extends parallel to the x-axis, and similarly, the link 34 extends parallel to the x-axis. When the toe portion 20 and the heel portion 50 are grounded, the distance on the x-axis from the joint 31 to the joint 33 is substantially the same as the length of the guide portion 22 on the x-axis.

  As shown in FIG. 4, the link 34 passes through the openings provided in the wall portion 57 a and the pulley 63 and engages with the nut portion 65. The link 34 and the nut portion 65 constitute a “ball screw” as described above. For example, a ball traveling path (for example, the traveling path extends in a spiral shape) is provided on the outer peripheral surface of the link 34. The nut portion 65 is also provided with a ball advancing passage. When the passages of the link 34 and the nut portion 65 are continuous, both are engaged. A large number of balls are arranged without gaps in a traveling passage formed continuously between the link 34 and the nut portion 65. By rotation of the nut portion 65, each ball circulates in the above-described passage, and accordingly, the link 34 advances and retreats with respect to the nut portion 65. In this way, the link 34 is advanced and retracted by the rotation of the nut portion 65. The advance / retreat control of the link 34 may be realized by using means other than the ball screw.

  The operation | movement which the collar part 50 is lifted from a ground surface is implement | achieved by the following mechanism, for example. First, the electric motor 61 is driven, and the rotating shaft of the electric motor 61 is rotated. When the rotating shaft of the electric motor 61 rotates, the pulley 62 also rotates. When the pulley 62 rotates, the pulley 63 around which the common belt 64 is turned rotates. When the pulley 63 rotates, the nut portion 65 also rotates. When the nut portion 65 rotates, the link 34 moves in a direction approaching / separating toward the flange portion 50 side. For example, when the nut portion 65 rotates to the right, the link 34 moves upward as viewed from the front in FIG. When the nut portion 65 rotates counterclockwise, the link 34 moves downward as viewed in front of FIG. As schematically shown in FIG. 5, by adjusting the length of the link 34 existing on the tip side of the nut portion 65, the inclination angle of the flange portion 50 with respect to the ground contact surface is set with the rotation axis AX as the rotation axis. Will be adjusted.

  The joint structure 100 constitutes a foot part of a walking robot having one or more leg parts. When the joint structure 100 is separated from the ground contact surface, the heel portion 50 rolls and moves on the ground contact surface toward the toe portion 20 in a state where the tip toe portion 20 is grounded. Usually, when the flange 50 is separated from the ground contact surface, a frictional force is generated. Therefore, it is required to generate a torque between the toe portion 20 and the flange 50 so as to overcome the frictional force. In this embodiment, in order to reduce the influence of this frictional force, the collar part 50 is rolled and moved on the ground contact surface to the toe part 20 side. More specifically, a rotation axis AX is provided for the heel part 50, and this rotation axis AX is synchronized with the separation of the heel part 50 from the grounding surface, and moves the top of the toe part 20 to the tip side of the toe part 20. Moving. As a result, the flange 50 rolls on the ground contact surface, and therefore it is possible to suppress the influence of the frictional force. In addition, the use of the joint structure 100 is arbitrary, and should not be limited to the feet of the walking robot.

  A process of deforming the joint structure 100 will be described with reference to FIG. The joint structure 100 is deformed in the order of FIG. 5A to FIG.

  As shown in FIG. 5A, the toe portion 20 and the heel portion 50 are grounded. The length of the link 34 extending from the wall portion 57a to the distal end side (hereinafter sometimes referred to as the extension length of the link 34) is W10. The rotation axis AX is at a position separated from the rear end surface of the guide portion 22 by the width W11.

  As shown in FIG. 5B, the flange 50 is lifted with an inclination of θ20 degrees (not θ20 degrees = 20 degrees) with respect to the ground plane. In synchronization with the extension length of the link 34 being adjusted to be shortened from W10 to W20, the flange portion 50 is inclined by θ20 degrees with respect to the ground plane. The rotation axis AX is at a position separated from the rear surface of the guide portion 22 by the width W21 (width W11 <width W21).

  As shown in FIG. 5C, the flange 50 is lifted with an inclination of θ30 degrees (not θ30 degrees = 30 degrees) with respect to the ground plane. In synchronization with the extension length of the link 34 being adjusted to be shortened from W20 to W30, the flange portion 50 is inclined by θ30 degrees with respect to the ground plane. The rotation axis AX is at a position separated from the rear surface of the guide portion 22 by the width W31 (width W21 <width W31). It can be seen that the rear end of the link 34 has moved to the vicinity of the rear end of the base plate 53.

  As can be understood from the disclosure of FIG. 5, in synchronization with the extension length of the link 34 being adjusted to be short, the collar part 50 is rotated with respect to the toe part 20, and the collar part 50 is separated from the ground surface, At the same time, the flange 50 rolls on the ground plane. In other words, in synchronization with the extension length of the link 34 being shortened, the flange portion 50 rotates with respect to the toe portion 20, and the rotation axis AX moves on the toe portion 20. Thereby, the separation operation from the ground contact surface can be realized in a mode in which the influence of the frictional force is suppressed. The tip portion of the shaft holding portion 55 is formed in a circular shape. Therefore, the shaft holding portion 55 can suitably roll on the ground surface toward the front (left side when FIG. 5 is viewed from the front). Such rolling can reduce the torque required for the relative displacement of the flange portion 50 with respect to the toe portion 20, and can reduce the power consumption of the electric motor 61.

  With reference to FIG. 6, the specific aspect in which the rotating shaft AX provided in the collar part 50 is engaged with the toe part 20 will be described. FIG. 6B is a schematic cross-sectional view taken along the alternate long and short dash line in FIG.

  As schematically shown in FIG. 6B, a transmission 41 and a pinion 43 are arranged on the rotation axis AX. The rotation axes of the pinion 43 and the transmission 41 coincide with the rotation axis AX. The transmission 41 is provided to adjust the rotation amount of the pinion 43 and the rotation amounts of the circular portions 55b and 56b, as will be described later. The pinion 43 meshes with a rack 27 provided on the upper surface of the flat plate portion 22a. As the pinion 43 moves on the rack 27, the rotation axis AX moves on the rack 27.

  As shown in FIG. 6B, on both sides of the pinion 43, a pair of sliders (slider 42 and slider 44) protruding in the vertical direction are provided. The upper portion of the slider 44 is guided by a concave guide rail 22b1 provided in the frame-like portion 22b. The upper portion of the slider 42 is guided by a concave guide rail 22c1 provided in the frame-like portion 22c. The lower portion of the slider 44 is guided by a concave guide rail 22a1 provided on the flat plate portion 22a. The lower portion of the slider 42 is guided by a concave guide rail 22a2 provided on the flat plate portion 22a. By the guide mechanism (guide mechanism) including the slider and the guide rail, it is possible to ensure that the pinion 43 (the rotation axis AX) linearly moves along the x axis. By moving the pinion 43 (rotating axis AX) linearly along the x-axis, it is possible to ensure a state where the circular portions 55b and 56b roll stably and continuously on the ground surface.

The reason why the transmission 41 is provided will be described with reference to FIG. As shown in FIG. 7 (a), the radius of the pinion 43 and _{r p,} the radius of rotation of the circular portion 56b and _{r h.} At this time, the reduction ratio of the transmission 41 is obtained as follows.
Reduction ratio of transmission 41 = r _h / r _p

As shown in FIG. 7 (b), when the rotation angle = theta, rolling amount d _h of the rolling amount d _p and circular portion 56b of the pinion 43 is calculated as follows.
d _h = r _h × θ
d _p = r _p × θ × (r _h / r _p ) = r _h × θ

Gear ratio of the transmission 41 is adjusted to match each other and the rolling amount d _h of the rolling amount d _p and circular portion 56b of the pinion 43. By rolling amount d _h of the rolling amount d _p and circular portion 56b of the pinion 43 match, can be circular portion 56b is configured so that no slipping when moving over the ground surface. The relationship between the pinion 43 and the circular portion 56b is the same as the relationship between the pinion 43 and the circular portion 55b. The rotation center of each circular portion is located on the rotation axis AX, like the rotation axis of the pinion 43. Similarly, the rotation shaft of the transmission 41 is positioned on the rotation shaft AX.

  A process of moving the pinion 43 on the rack 27 will be supplementarily described with reference to FIGS. 9A to 9C are schematic cross-sectional views taken along the alternate long and short dash line in FIG. 9A to 9C, the extension length of the link 34 is adjusted to be short.

  As shown in FIG. 9A, the toe portion 20 and the heel portion 50 are grounded. The rotation axis AX of the pinion 43 is at a position separated from the rear end position of the rack 27 by the width W11.

  As shown in FIG. 9B, the flange portion 50 is lifted with an inclination of θ20 degrees with respect to the ground contact surface. The rotation axis AX of the pinion 43 is at a position separated from the rear end position of the rack 27 by the width W21 (width W11 <width W21).

  As shown in FIG. 9C, the flange 50 is lifted with an inclination of θ30 degrees with respect to the ground contact surface. The rotation axis AX of the pinion 43 is at a position separated from the rear end position of the rack 27 by a width W31 (width W21 <width W31).

  As can be understood from the disclosure of FIG. 9, the pinion 43 rolls on the rack 27 in synchronization with the extension length of the link 34 being adjusted to be short. In synchronization with the rotation of the pinion 43, the circular portion 55b rolls on the ground plane. The rack 27 extends in the horizontal direction, and the pinion 43 moves horizontally on the rack 27. Accordingly, the circular portion 55b also moves horizontally along the contact surface while maintaining the contact state.

  10 and 11 are perspective views schematically showing changes in the joint structure 100. FIG.

  As shown in FIG. 10, in the joint structure 100, the collar portion 50 rotates and moves toward the distal end portion 21 with the distal end portion 21 being grounded. Since the tip of each shaft holding part of the collar part 50 is formed in a circular shape, the rotational movement of the collar part 50 can be suitably performed. Thereafter, the heel portion 50 is in a state of being grounded only by the circular portion, and finally leaves the ground surface together with the toe portion 20. It should be noted that the timing at which the collar portion 50 is separated from the ground surface and the timing at which the tip portion 21 is separated from the ground surface are preferably substantially the same, but this is not restrictive.

  FIG. 10 is a perspective view of the posture change of the joint structure 100 through the grounding surface from below the grounding surface. As shown in FIG. 10, the collar part 50 moves forward as the collar part 50 moves away from the ground contact surface. A receiving space for receiving the guide portion 22 is provided between the shaft holding portion 55 and the shaft holding portion 56. Thereby, it can suppress effectively that the guide part 22 and the base board 53 interfere.

  As shown in FIG. 11, the link 34 gradually extends rearward from the wall portion 57 c as the flange portion 50 moves away from the ground surface. This occurs as a result of the shortening of the length of the link 34 extending forward from the wall 57a.

  The wall 57c is provided with an opening through which the link 34 functioning as a screw shaft can pass. The same applies to the wall 57a.

Embodiment 2
The second embodiment will be described with reference to FIG. As schematically shown in FIG. 12, a layered elastic member 90 having a constant thickness is attached to the bottom surface of the base plate 53. In the process of floating the flange 50 from the ground contact surface, the load applied to the elastic member 90 decreases from the rear to the front of the flange 50. At this time, if the collar portion 50 moves away from the ground contact surface in a short time, the floor reaction force suddenly does not exist, and the distribution of the floor reaction force may not be changed slowly. In this embodiment, the elastic member 90 is provided with respect to the bottom face of the collar part 50 in view of this point. As a result, it is possible to slowly change the distribution of the floor reaction force that the flange 50 receives from the ground contact surface (smoothly change the distribution of the floor reaction force toward the toe portion 20 side). In a suppressed manner, the joint structure 100 can be floated from the ground plane.

  According to the present embodiment, when the joint structure 100 is incorporated in the robot as a foot part of the robot, the stability of the entire robot is effectively suppressed from deteriorating due to the ZMP (Zero Moment Point) shifting backward. Can do. ZMP is an action point when the normal component of the floor reaction force distributed over the entire sole is replaced with a certain point. In recent robots, the ZMP position is calculated and the drive system is controlled so that the ZMP position is within a predetermined range. The material of the elastic member 90 is, for example, resin or the like, but is not limited thereto and is arbitrary.

Embodiment 3
Embodiment 3 will be described with reference to FIG. As shown in FIG. 13, joint structure 100 shown in the first or second embodiment constitutes a foot portion of robot 200. Even in such a case, the same effects as those of the first and second embodiments can be obtained. As illustrated in FIG. 13, the robot 200 includes a trunk portion 201, arms 202 and 203 including a plurality of joints, and leg portions 204 and 205 including a plurality of joints. The robot 200 moves in space by bipedal walking in response to an independent or external command. It should be noted that the target for incorporating joint structure 100 is not limited to such a biped robot.

Reference Explanation A reference explanation will be given below with reference to FIGS. Based on the following description with reference to FIGS. 14 to 18, the disclosure content of the above-described embodiment may be grasped.

  As shown in FIG. 14, the case where the toe portion 301 and the heel portion 302 are connected via the rotation mechanism 303 will be considered. As shown in FIG. 14A, when the collar 302 is lifted from the ground surface by the rotation control of the rotation mechanism 303, the friction force indicated by the arrow in FIG. 14B is caused by the friction between the collar 302 and the floor. It will occur.

  In order to reduce the above-mentioned frictional force, a solution means shown in FIG. 15 can be considered.

  As shown in FIG. 15A, it is conceivable to reduce the frictional force by reducing the height of the rotating mechanism 303. However, the size of the rotation mechanism 303 cannot be ignored, and it is necessary to avoid interference with the toe part 301 or the hook part 302. Therefore, there is a limit to reducing the height of the rotation mechanism 303. .

  As shown in FIG. 15B, it is conceivable to reduce the frictional force by arranging the rotating mechanism 303 on the front side. However, even if the rotation mechanism 303 is disposed on the front side, there is a limit to the tip of the toe portion 301. In addition, it is not preferable from the viewpoint of design to dispose the rotating mechanism 303 in a conspicuous portion as viewed from the outside. If the rotation mechanism 303 is disposed in front, there is a problem that the degree of freedom in design design is impaired.

  As shown in FIG. 15C, it is conceivable to reduce the area of the bottom surface of the flange portion 302. However, the friction on the bottom surface of the collar 302 is necessary for maintaining a stable posture of the robot. Therefore, in the case shown in FIG. 15C, it is necessary to provide a material having a high coefficient of friction on the bottom surface of the flange 302, and as a result, the effect of reducing the frictional force is considered to be limited. It is done.

  As shown in FIG. 15 (d), it is conceivable to provide a rotating wheel for the collar 302. However, in order to maintain a stable posture of the robot, a mechanism for locking the rotating wheels is required, which in turn complicates the configuration.

  In the present embodiment described above, a sufficient frictional force can be ensured in the collar portion 302, so that the posture of the robot does not become unstable.

  As shown in FIG. 16, it is assumed that the friction coefficient of the ground contact surface on which the toe portion 301 is disposed is smaller than the friction coefficient of the ground contact surface on which the flange 302 is disposed. In this case, as schematically shown in FIG. 16A, when the heel part 302 is rotated upward, the frictional force applied to the heel part 302 is larger than the frictional force applied to the toe part 301. It is expected to grow. In this case, as a whole, as shown schematically in FIG. 16B, it is assumed that the vehicle slips forward.

  In the above-described embodiment, when the collar portion is rotated upward from the ground contact surface, it is suppressed that a large frictional force is applied to the collar portion. Therefore, even when walking on contact surfaces with different friction coefficients, the walking state can be suppressed from becoming unstable.

  As schematically shown in FIG. 17, when the collar is lifted from the ground plane, the ground contact area of the collar with respect to the ground plane is rapidly reduced. At this time, there is a problem in that the position of the ZMP is displaced and cannot be handled even if feedback control is performed. As shown in FIG. 17A, a floor reaction force distribution is given to the toe portion 301 and the heel portion 302. As shown in FIG. 17B, a moment is generated in which the collar 302 is lifted from the ground surface and falls backward as schematically indicated by an arrow. Then, as shown in FIG.17 (c), ZMP will shift | deviate backward. If the positional deviation of the ZMP is large, the robot may fall over.

  In order to solve the problem related to the ZMP displacement, it is preferable to attach a layered elastic member 304 to the bottom surface of the collar 302 as shown in FIG. In this case, when the eaves part 302 is lifted from the ground contact surface, the distribution of the floor reaction force shown in FIG. 18A changes to the floor distribution shown in FIG. Thus, by providing the elastic member 304, the transition of the floor reaction force becomes slow, and the influence of the positional deviation of the ZMP can be suppressed by the operation of the attitude control feedback system. However, even if it is a case shown in FIG. 18, the frictional force which arises when the collar part 302 floats from a ground-contact surface is not reduced. Therefore, it is necessary to generate a torque sufficient to overcome the frictional force in FIG.

  In Embodiment 2 of the embodiment, the frictional force applied to the buttocks when floating the buttocks is small. Therefore, in the second embodiment, an elastic member can be bonded to the bottom surface of the buttocks, and resistance to ZMP positional deviation can be imparted to the joint structure.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, the movement mode of the rotating shaft that moves on the toe portion is arbitrary, and is not limited to linear movement. The specific mode in which the rotating shaft is held by the toe portion is arbitrary. The specific shape of the toe / buttock is arbitrary. A drive mechanism other than a ball screw may be employed. The number of joints provided in the joint structure is arbitrary.

100 joint structure

20 toe part 21 tip part 22 guide part 50 collar part

30 Link mechanism

41 Transmission 42 Slider 43 Pinion 44 Slider

27 racks

53 Base plate 55 Shaft holding portion 55a Extending portion 55b Circular portion 56 Shaft holding portion 56a Extending portion 56b Circular portion

61 Electric motor 62 Pulley
63 pulley
64 Belt 65 Nut

80 Top plate

Claims (12)

A joint structure including first and second members separated in this order from the ground plane,
The first member includes a rotation shaft engaged with the second member,
The rotating shaft is configured to be movable on the second member along the grounding surface in accordance with the rotation of the first member with respect to the second member. The first member includes a shaft holding portion that holds the rotation shaft,
The joint structure according to claim 1, wherein the shaft holding portion is configured to be capable of rotating on the ground surface in accordance with the rotation of the first member with respect to the second member. The first member includes a shaft holding portion that holds the rotation shaft, and the shaft holding portion is configured to be able to rotate on the ground surface in accordance with the rotation of the first member with respect to the second member. The joint structure according to claim 1 or 2, wherein
A rotation ratio adjusting mechanism for adjusting a rotation ratio between the rotation shaft and the shaft holding portion is further provided. The first member includes a set of shaft holding portions that hold the rotating shaft,
The space for avoiding interference between the first and second members during the movement of the rotating shaft is provided between the pair of shaft holding portions. The joint structure as described in any one of thru | or 3.   5. The joint structure according to claim 1, wherein the first member and the second member are provided with a guide mechanism that guides the movement of the rotation shaft. The first member includes a pinion having the rotation shaft as its rotation shaft,
The joint structure according to any one of claims 1 to 5, wherein the second member includes a rack in which the pinion is engaged. In a mode that allows rotation between the first member and the second member, a link mechanism that connects the first and second members is further provided,
The drive mechanism for moving the link included in the link mechanism forward and backward as viewed from the first member is provided in the first member. Joint structure.   The said 2nd member contains the front-end | tip part which earth | grounds with respect to a grounding surface, and the guide part in which the movement path of the said rotating shaft was provided, The Claim 1 thru | or 7 characterized by the above-mentioned. Joint structure.   The joint structure according to any one of claims 1 to 8, wherein an elastic member is provided on a bottom surface of the first member. The first member is a buttock corresponding to a heel of a human foot,
The joint structure according to any one of claims 1 to 9, wherein the second member is a toe portion corresponding to a toe of a human foot.   A robot comprising the joint structure according to any one of claims 1 to 10. The first and second members are sequentially separated from the ground surface, and the rotation shaft provided on the first member is an operation method of the joint structure engaged with the second member,
In response to the rotation of the first member relative to the second member, the rotation shaft moves on the second member along the grounding surface,
The operation method of the joint structure, wherein the first member rolls on the grounding surface in response to the rotation of the first member with respect to the second member.

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